Southern Asia: India

Although not exceptionally outstanding for biological richness or endemism by itself, the South Deccan Plateau Dry Deciduous Forests [IM0209] ecoregion is contiguous with the moist deciduous forests that lie along the foothills of the southern extent of the Western Ghats Mountains. Two of India's most important elephant conservation areas, the Nilgiris-Eastern Ghats and the Anamalais-Nelliampathis (Sukumar 1989), and two of the most important TCUs (Wikramanayake et al. 1999) extend across three ecoregions: the South Western Ghats Montane Rain Forests [IM0151], South Western Ghats Moist Deciduous Forests [IM0150], and South Deccan Plateau Dry Deciduous Forests [IM0209]. Together, these three ecoregions provide an important, contiguous habitat landscape for conservation of Asia's largest terrestrial herbivore and predator.

Scientific Code

(IM0209)

Ecoregion Category

Indo-Malayan

Size

31,800 square miles

Status

Critical/Endangered

Habitats

Description Location and General DescriptionThe ecoregion represents a large area of tall, tropical dry forests in the southern Deccan Plateau, on the leeward side of the Western Ghats Mountain Range. It extends across the southern Indian states of Karnataka and Tamil Nadu. The ecoregion's links to the ancient, southern circumpolar continent, Gondwanaland, are evident in the biotic links to Africa and Madagascar (Meher-Homji 1989).

The ecoregion's vegetation is highly influenced by climate. The tall Western Ghats Mountain Range intercepts the moisture from the southwest monsoon; therefore, the eastern slopes and the Deccan Plateau receive very little rainfall; annual rainfall ranges from 900 to 1,500 mm. The undulating hillsides have very shallow soils.

The dry deciduous forests of this ecoregion are flanked by the moist deciduous forests along the lower elevations and foothills of the Western Ghats to the west and by thorn scrub to the east. Therefore, this ecoregion probably represents a transition zone between the moister western vegetation and the drier vegetation to the east.

Champion and Seth (1968) classified these forests as Southern Dry Mixed Deciduous Forests, where teak (Tectona grandis) is not conspicuous. Thorny plants become more common in areas where grazing pressure is high.

Structurally, these dry forests have a three-storied forest, with an upper canopy at 15-25 m, an understory at 10-15 m, and undergrowth at 3-5 m (Puri et al. 1989). Lianas drape the trees in denser, mature forests. The vegetation is characterized by Boswellia serrata, Anogeissus latifolia, Acacia catechu, Terminalia tomentosa, Terminalia paniculata, Terminalia belirica, Chloroxylon swietenia, Albizzia amara, Cassia fistula, Hardwickia binata, Dalbergia latifolia, Sterospermum personatum, Pterocarpus marsupium, Diospyros montana, and Shorea talura, among others (Champion and Seth 1968). One of the important species of this forest, sandalwood (Santalum album), has been selectively removed from most of the forests in this ecoregion.

Biodiversity FeaturesAlthough not high in endemism or diversity, the ecoregion harbors several important populations of India's large threatened vertebrates whose populations are fast declining throughout their ranges because of habitat loss and hunting pressure. For instance, the elephant population that ranges from the Nilgiri Hills to the Eastern Ghats, estimated at more than 6,000 animals, is considered to be the largest single elephant population in India (Sukumar 1989). A second important population ranges along the Anaimalai and Nelliampathi Hills.

Two high-priority TCUs (Periyar-Kalakad and Dandeli-Bandipur) overlap with parts of this ecoregion (Wikramanayake et al. 1999).

An asterisk signifies that the species' range is limited to this ecoregion.

Two species in this ecoregion, the Indian bustard (Ardeotis nigriceps) and lesser florican (Eupodotis indica), are globally threatened and warrant conservation attention.

Current StatusMore than 80 percent of the ecoregion's forests have been cleared, but two large blocks of contiguous habitat remain in the north. There are seven protected areas that cover about 1,100 km2, or a little more than 1 percent of the ecoregion. But none of these exceed 500 km2; therefore, the ecoregion's protected area system is woefully inadequate to conserve the several large vertebrates in this ecoregion.

Ecoregion numbers of protected areas that overlap with additional ecoregions are listed in brackets.

Types and Severity of ThreatsMost of the dry deciduous forests represented by this ecoregion have already been degraded to thorn scrub (Champion and Seth 1968). The remaining forests are highly threatened with conversion to cash crop plantations, excessive fuelwood collection, and overgrazing by large herds of cattle. The habitat contiguity with the moist deciduous forests along the foothill of the Western Ghats, in particular, has been severed in several areas by conversion to agricultural lands. Large areas of forested land are lost to development projects such as dams, mining, and resettlement of displaced people. Many of the habitat areas that will be lost to large-scale hydroelectric projects now serve as refuges for the ecoregion's biodiversity. The conservation status of the ecoregion was changed from endangered to critical because of the threats from human population to the remaining forest blocks.

Poaching is a major threat in this ecoregion. The capacity to protect and manage the ecoregion's biodiversity is lacking, especially because these habitats are perceived as being unimportant for biodiversity conservation. Where conservation efforts have been made, poor planning has resulted in the introduction of exotic species and conversion of grassland and open scrub habitat that are important for many focal species such as bustards and floricans.

A major threat in the future will be the development of these areas for mining and industrialization. Licenses have been granted to exploit several areas in the ecoregion, and there is an urgent need to counter these initiatives by setting aside key areas for conservation of the ecoregion's representative biodiversity.

Justification of Ecoregion DelineationIn a previous analysis of conservation units, Rodgers and Panwar (1988), and subsequently MacKinnon (1997), divided the Deccan Peninsula into five biotic provinces. This ecoregion lies within Rodgers and Panwar's Deccan Plateau South (6A) biotic province. But this biotic province contains several vegetation types. Therefore, in keeping with our definition of an ecoregion (i.e., an ecosystem of regional extent) and following our rules for ecoregion delineation (representing distinct vegetation types of regional extent in separate ecoregions), we placed the tropical dry deciduous forests in this biotic province in the South Deccan Plateau Dry Deciduous Forests [IM0209]. We used MacKinnon's (1997) map of original vegetation to identify the extent of the dry deciduous forests and exclude the large areas of thorn forests.

ReferencesReferences for this ecoregion are currently consolidated in one document for the entire Indo-Pacific realm.Indo-Pacific Reference List